The long term goal of this research is to develop optical instruments and methods for measuring and imaging tissue temperature. In Phase 1, techniques will be developed that compute temperature readings from near-infrared absorption bands of water. The effect of interference on such measurements from other tissue components will be determined. In the initial studies to be performed during Phase I, the following tasks will be undertaken: -Determine wavelengths of water NIR absorption with high correlation to tissue temperature; -Select wavelengths that have good tissue penetration; -Determine the effect of optical bandpass on the sensitivity of the method in order to obtain optimal criteria for instrument design; -Examine effects of tissue components with NIR absorbances to determine their extent of interference, if any, and means for appropriate correction to the temperature prediction equation; -Test predicting equations on sample sets containing mixtures of interfering substances and simple tissue models; -Examine feasibility of adapting optical methods to depth-resolved measurements. In Phase 11 of this project, instruments will be constructed based on the methods developed in Phase I. These instruments will be tested and then used to measure tissue temperature measurements in areas of clinical interest.